land farming bioremediation treatability ...with molasses (carbon and energy source) and witconol (a...
TRANSCRIPT
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Land Farming Bioremediation Treatability Studies \2 D -for the
Popile, Inc. SiteEl Dorado, Arkansas
AUGUST 1,1997
submitted to:
UNITED STATES ENVIRONMENTAL PROTECTION AGENCYREGION 6
DALLAS, TX
by:
UNITED STATES ARMY CORPS OF ENGINEERS
NEW ORLEANS DISTRICT WATERWAYS EXPERIMENT STATIONNEW ORLEANS, LA VICKSBURG, MS
^ U.S. Environmental Protection Agency
US Army Corpsof Engineers »
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Table of Contents
List of TablesList of Append icesList of Figures
I. Summary
It. IntroductionA. History of Popile siteB. Data concernsC. Project Description
III. Objectives
IV. MethodsA. CoringB. Sample Preparation
VI. ResultsA. Initial characterization of soils
1. Physical2. Chemical3. Microbiological
B. Biotreatments1. pH neutralization of soil from soil holding cell2. Soil cell land farming microcosm studies3. Process area land farming microcosm studies4. Mixed process area and soil holding cell land
arming microcosm studies
VII. Discussion
VIII. Recommendations
IX. Tables
X. Appendix
XI. Figures
List of Tables
Table 1 . Factorial experimental design.
Table 2. Removal of total polycyclic hydrocarbons (PAH)and pentachlorophenol (PCP) from soil microcosms
Table 3. Summary of total PAH and PCP losses
Table 4. Total average % loss per soil area per microcosmtreatment
List of Appendices
Appendix
A. Results of an LSD-ANOVA for the comparison of tPAHconcentrations across treatments; initial versus final
concentrations.
B. Results of an LSD-ANOVA for the comparison of PCP 21concentrations across treatments; initial versus finalconcentrations.
C. Polycyclic aromatic hydrocarbon and pentachlorophenol 22concentrations in replicate respirometer flasks.
D. Polycyclic aromatic and pentachlorophenol concentrations 23as averages and standard deviations from replicate respirometerflasks.
List of Figures
pageFigure 1 . Obtaining core samples. 25
Figure 2. Sample preparation. 26
Figure 3. Comparison of results of contaminant analysis. 27
Figure 4. Construction of soil holding cell and initial chemical 28and physical characterization.
Figure 5a. Viable microbial biomass estimates. 29
Figure 6. ^C-Acetate mineralization study. 30
Figure 7. Soil cell pH neutralization study. 31
Figure 8. ^-Pentachlorophenol mineralization in soil cell land 32farming microcosms.
Figure 9. Mass balance of radiolabeled PCP in soil cell land 33farming microcosms.
Figure 10. Soil cell land fanning microcosms. 34
Figure 1 1 . Soil cell land fanning microcosms. 35
Figure 12. Soil cell land farming microcosms. 36
Figure 13. ^C-Pentachlorophenol mineralization in process 37area soil land farming microcosms.
Figure 14. Mass balance of radiolabeted PCP in process area 38soil land farming microcosms.
Figure 15. Process area soil land farming microcosms. 39
Figure 16. ^C-Pentachlorophenol mineralization in mixed process 40area and soil cell soil land farming microcosms.
Figure 17. Mass balance of radiolabeled PCP in mixed process area 41and soil cell land farming microcosms.
Figure 18. Mixed process area and soil cell soil land farmingmicrocosms.
Figure 19. Mixed process area and soil cell soil land farmingmicrocosms.
Figure 20. Mixed process area and soil cell soil land farmingmicrocosms.
page42
43
44
Figure 21. Statistical comparison of soil cell treatment means. 45
Figure 22. Statistical comparison of process area soil treatment means. 46
Figure 23. Statistical comparison of mixed process area and soil 47cell soil treatment means.
POPILE SUPERFUND SITEEL DORADO, AR
LAND FARMING BIOREMEDIATION TREATABILITY STUDY
Summary
The Popile Inc. Site is a former wood-treating facility located in ElDorado, Arkansas. The primary contaminants found at the site includepentachorophenol (PCP) and creosote compounds associated with woodtreatment. The proposed remedy of the site soils involves excavation andtreatment of approximately 165,000 cubic yards of contaminated soils andsludges in onsite land treatment units .
Two different types of contaminated soils exist on the site which will behandled separately. Soil holding cell soils consist of highly contaminatedprocess pond sludges stabilized with fly ash and rice hulls at pH 9.6. Oldprocess area soils (pH 7.1) were incidentally contaminated through normal useof the facility. Material in the soil holding cell is hardest to bioremediate and willbe the focus of the treatability study. The old process materials will be mixedwith the soil holding cell material as a variable to study the effects of dilutionand introduction of additional native microbes.
USAGE cannot conclude from any data reviewed to date that reachingthe remedial levels of 3 ppm for B(a)P and 5 ppm for POP is possible. Amicroscale treatability study was initiated to provide additional feasibility dataon treatability of the site specific soils using land farming techniques. A seriesof static microcosms containing 40g of homogenized soil cores were used tosimulate landfarming treatments on soil holding cell soil, process area soil anda 1:1 mixture of the two area soils.
Both process area and soil holding cell soils had estimated viablemicrobial biomass of 7.7x 107 cells per gram dry weight soil. Comparison ofmicrobial community phospholipid profiles indicated that process area and soilholding cell soils were composed of different types of bacteria. ^C-acetatemineralization after 7 days was greater than 90% in unamended process areasoils indicating a healthy, aerobic microbial population. ^C-acetatemineralization was low, less than 55%, in either unamended or pH neutralizedsoil holding cell soils and 1:1 mixtures of soil holding cell soil with process areasoil.
The effects of four variables on ^C-PCP mineralization rates werestudied: pH adjustment (sulfuric acid or acetic acid), carbon/energy sources(molasses or acetic acid), surfactant (wrtconol), in addition to dilution andinoculation of highly contaminated soil holding cell soil with process area soil(1:1 mixture). Respiration of ^C-C02 from ^C-PCP did not exceed 10% after100 days in any system tested, indicating the majority of added ^C-PCP wasnot mineralized. Analysis of net tPAH and PCP levels in soil holding cell soilstreated in 150-day land farming simulations indicated no significant contaminantreduction in any treatment. In contrast, process area soil landfarmingsimulations with no additives or 3% wrtconol resulted in 92 - 94% reduction innet tPAHs, reduction from 42 B(a)Peq to 8 B(a)Peq and removal of PCP tobelow detection limits (<1 ppm). Dilution of soil holding cell soil with processarea soil had no significant effect on contaminant reduction in any treatment.
In summary, cleanup goals for B(a)Peq and PCP by land farming ofprocess area soil are supported by microscale studies. The four variablesexamined were not effective in increasing soil holding cell soil contaminantremoval rates to achieve cleanup goals. No advantage in PCP or PAH removalrates was gained when SC and PA soils were mixed before treatment, ascompared to separate treatment of the soils. Results from these microscalestudies indicate that mesoscale studies should focus on no amendment and 3%wrtconol amendment land farming simulations with process area soil. Notreatment can be recommended for soil holding cell soil. Alternative treatmentsmust be sought to achieve ROD cleanup goals in soil holding cell soils.
II. Introduction
A. History of Popile.
The Popile Inc. site is a former wood-treating facility located in ElDorado, Arkansas. The primary contaminants found at the site includepentachorophenol (PCP) and creosote compounds associated with woodtreatment. Wood treatment operations ceased in July 1982. The site waspurchased by Popile, Inc. In 1984, Popile consolidated three impound pondsinto to one. This closure activity was administered by the Arkansas Departmentof Pollution Control and Ecology. In 1988 and 1989 an EPA field investigationrevealed contaminated soils, sludges and ground water at the site. EPAdetermined that an emergency removal action was necessary and wasconducted from September 1990 to August 1991. The emergency actionconsisted of modifying site drainage, placing and seeding topsoil, solidifyingand placing sludges into an onsite soil holding cell.
The EPA's design contractor, Camp, Dresser and McKee, FederalPrograms was tasked with development of the RemedialInvestigation/Feasibility Study. After approval, Camp, Dresser and McKee,developed of the plans and specifications for the Popile site. The remedyinvolves the excavation and treating of approximately 165,000 cubic yards ofcontaminated soils and sludges in onsite land treatment units . Indigenousmicroorganisms were expected to break down target contaminants to lessharmful and less mobile constituents.
Two types of contaminated soils exist on the site. The first is the soilholding cell material, consisting of soils stabilized with rice hulls and fly ash (pHapproximately 10) under previous emergency remedial activities. The second issoils from the old process area which consist of soils that were contaminated byspills and leaks during wood treatment activities. The two different areas ofcontaminated soil on the site represent two different study populations.
B. Data Concerns.
Insufficient data exists to validate ROD goals and to establish contractduration for full scale bioremediation of soils. The plans and specificationstipulate that a contractor must meet the remediation goals of 3 ppm for B(a)Pand 5 ppm for PCP in order to met the performance results of the specification.The Record of Decision establishes those same remediation levels as "goals"and implicitly casts doubt as to the attainability of those remediation levels.Preliminary treatability data supplied by the EPA Kerr Laboratory indicates thatit may not be possible to reach those levels. Additionally, USAGE cannotconclude from any data reviewed to date that reaching the remedial levels ispossible. This additional study was in accordance with that recommended inthe first treatability study performed by EPA Environmental ResearchLaboratory at Ada, Oklahoma.
C. Project Description
The experimental approach for the study will be performed in fourexperiments. Material in the soil holding cell was expected to be the mostdifficult to bioremediate and was the focus of the treatability study. The oldprocess area soil was mixed with the soil holding cell material as a variable tostudy the effects of dilution and introduction of additional native microbes.
The first was a titration experiment, designed to determine how to handlethe stabilized soil from land cell so its phi can be neutralized while minimizingthe injury to the soil's microflora . The soil cell area currently has a pH of 9.6.
To determine the relative "health" or microbial biomass of the two soils, totalamounts of phospholipids extracted from each soil were used to estimatenumbers of bacteria.
The second is a microbial seed indicator study on the process area soils,conducted solely at the micro-scale. It was proposed to use the process areasoil in both dilution of disposal cell area soil and to provide an inoculum ofbacteria to enhance biodegradation in the soil cell area soil. To assess theprocess area soils ability to provide microflora for degradation of PCP, a micro-scale study will be conducted in shaker flasks with process area soil. Toxiceffects of soil contaminants will be assessed by measuring the ability of studysoils in flasks to utilize C^-acetate as a simple carbon source. Radioactivepentachlorophenol (C^-PCP) will be introduced into the flask soils, so thatradioactive C^-COz can be monitored to track degradation of PCP during thestudy. Final mass balances will be performed to measure mineralization anddisappearance of contaminants by other mechanisms.
Objectives
1. To evaluate the efficacy of land farming for the removal of PAH and PCPfrom contaminated Soil Cell and Process Area soils.
2. To determine the effects of pH neutralization of SC soil using acetic andsulfuric acids.
3. To determine the effects on contaminant bioremediation of amendmentswith molasses (carbon and energy source) and Witconol (a surfactant).
4. To determine the effects on contaminant bioremediation of mixingProcess Area and Soil Cell soils to introduce indigenous microbes to thesystem.
5. To use the information generated to determine which biotreatments forPopile should be evaluated further at the bench engineering scale andpossible full scale operation.
The factorial design included the following treatments (Table 1): 1) pHneutralization with acetic acid; 2) pH neutralization with sulfuric acid; 3) additionof molasses as a carbon/energy source; and 4) mixing SC with PA to provide adegradative inoculum.
Additional funding from DoD's Strategic Environmental Research andDevelopment Program's Federal Integrated Biotreatment Consortium enabledthe scope of this study to be expanded. The expanded study (Table 1) included
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a 5th treatment, surfactant addition to the land farming study, and included aland farming efficacy evaluation of appropriate augmentations to the PA soil.
IV. Methods
Detailed descriptions of the methods used in this study can be found inthe Quality Assurance Project Plan (QAPP). If methods change or differentmethods are used, the QAPP will be changed and are detailed in this report
A. Sampling Coring
Obtaining samples representative of each soil type is essential toensuring that the results of the laboratory studies can be extrapolated back tothe environmental situation. New Orleans District (NOD) United States Corps ofEngineers (USCOE) engineers, assisted by Waterways Experiment Station(WES) scientists, visited the Popile site on June 25,1996 and sampled the Soilholding Cell (SC) and Process Area (PA) using a drill rig and 6 foot Shelbycoring tubes (Figure 2). Cores from three locations in the SC and threelocations in the PA were collected separately (reference Field Sampling Plan).The tubes were sealed on both ends and shipped to WES. Chain of custodyprotocols were followed.
B. Sample Preparation
On 27 June 1996, Shelby tubes of the SC soil and PA soil were extrudedwith a portable hydraulic RAM (furnished by NOD) at the Hazardous MaterialHandling Facility at WES (Figure 3). Following extrusion of samples, soil coreswere logged and geologically characterized by a NOD geologist. The geologicalreport is available from NOD. SC and PA soil samples were placed in separateplastic-lined 55 gallon drums and placed in a storage cooler at 5° C. SC soilrecovered from the Shelby tubes was homogenized in a 3 step process. First,SC soil was placed into a large flat metal container and treated with a roto-tiller.Second, the soil was mixed using shovels. Third, the soil was passed through a5-mm wire mesh sieve (Figure 3). This 3-step process was repeated with thePA soil.
Homogeneity of soils was determined by PAH and PCP analysis of 10replicate 15-g soil samples from homogenized SC and PA soils. Pooled soilcores were considered homogenized when coefficient of variations ofcontaminant analysis was less than 15% of the mean.
11
Quality control and validation of analytical analysis performed in housewas determined by independent analysis of split replicate samples for PAH andPCP levels at the beginning of microcosm studies. Split, replicate samples wereanalyzed by WES's Environmental Chemistry Branch (ECB). The accuracy ofthese determinations was verified by comparing the results of the Bligh-Dyerextraction method to those obtained using EPA Standard 3550 (Figure 4).Differences between methods were found to be significant for threecontaminants: naphthalene, fluorene and PCP. The decreased recovery for the2 volatile PAHs with the Bligh-Dyer protocol can be attributed to the use ofnitrogen to reduce the volume of solvent. The increased recovery of PCP withthe Bligh-Dyer protocol can be attributed to the ability of the Bligh-Dyerextraction mixture to penetrate and wet soil particles and its ability to extractpolar molecules.
VI. Results
A. Initial Characterizations of Soil Cell and Process Area Soils
1. Physical - Geological characterization of SC and PA soil cores was recordedby NOD as the cores were extruded from the Shelby tubes (Figure 2). Themoisture contents of the SC and PA soils were 12 to 20%. The pH levels of theSC and PA soils were 9.6 and 7.1, respectively.
2. Chemical- The levels oftPAH and PCP in SC and PA soils weredetermined by gas chromatography (equipped with a capillary column and aflame ionization detector). tPAH and PCP were identified by co-elution from the30m capillary column with authentic standards. Contaminants were quantifiedby integrating the area under the contaminant peak and relating this peak areato that of a known amount of contaminant standard. Identifications in a selectedno of samples was confirmed by gas chromatography - mass spectrometry.
The mean concentrations oftPAH in the SC and PA soils were 1459 +/-204 mg/kg and 2093 +/- 268 mg/kg, respectively (Figure 1). Mean PCPconcentrations in the SC and PA soils were 100 +/- 8 mg/kg and 55.6 +/- 8mg/kg, respectively (Figure 1).
3. Microbiological- The biomass and community composition of the microbialcommunities in the SC and PA soils were determined by extraction andanalysis of membrane polar lipid fatty acids (Figure 6A). The biomass andcommunity compositions of the SC and PA soil resident microflora were similar.Both soils had a biomass of approximately 7.7 x 107 cells per gram dry weight.Although differences in functional groups were apparent, both soils weredominated by Gram-negative members (Figures 5A & 5B). From this
12
perspective the SC and PA soils are normal relative to other surface soils. Dueto the length of time the cores were held in cold storage prior to analysis areduction in observed community differences can be expected.
All soils studied were challenged with ^C-acetate to determine thebasal aerobic respiration rates of resident microbial communities (Figure 6).^C-acetate respiration of the PA soil indicated a normal healthy soil. Eventhough the biomass and composition of the SC soils microbial communityappeared normal, ^C-acetate respiration was only 25% that of the PA.Additionally, neutralization with either sulfuric or acetic acid, and mixing PA andSC soil only partially increased ^C-acetate respiration in the SC soil.
B. Biotreatments.
1. pH Neutralization Experiments on Soil from the Soil Holding Cell - SC soilslurries (40% wt/vol) were suspended in a 250-ml glass beaker containing aTeflon-coated magnetic stirring bar by mixing them on a magnetic stirring plate.Either 1 N acetic or sulfuric acid was added to the suspension drop-wise usinga buret. The pH was measured with a calibrated pH electrode and recordedover a 24 hour period. Seventy-five micromoles of sulfuric add (0.075 ml of 1N) and 2.5 millimoles of acetic acid (2.5 ml of 1 N) were required to lower thepH of SC soil suspensions to 6.8 (Figure 7). No rebound in pH was recordedduring the 24 hours the experiment was conducted.
2. Soil Cell Soil Land Farming Microcosm Studies - Uniformly ring-labeled ^C-pentachlorophenol (98% radiochemically pure) was added to SC land farmingmicrocosms to provide a facile means of monitoring the rates of mineralizationof PCP. The cumulative ^C-COa evolved from the land farming microcosmsnever exceeded 2% and there were little or no significant differences betweenthe treatments (Figure 8). No ^C-pentachlorophenol was mineralized underany of the land farming treatments tested. A mass balance of C wascalculated for each microcosm receiving ^C-pentachlorophenol. The recoveryof ^C from the microcosms was good (Figure 9). After 150 days, the majority ofthe ^C initially added as ^C-pentachlorophenol was in the solvent extractablephase (generally 20-40%) or was bound so tightly to the soil it could only berecovered by combustion to ^C-CO; (generally 50%).
The levels of each PAH and PCP in soils from each of the land farmingmicrocosm treatments were compared to the respective levels before treatment(Figures 10-12). No land farming treatment effectively removed thecontaminants from SC soil (Figure 21).
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3. Process Area Soil Land Farming Microcosm Studies - Process area soilmicrocosms showed no significant production of ^C-COs from ^C-pentachlorophenol with either carbon or surfactant amendments (Figure 13).Recoveries of ^C from the microcosms were generally 90% or better. Massbalance results were similar for all three treatments. They showed > 75% of the^C was not extractable and could only be released from the soil by combustion(Figure 14). The two amended microcosms showed that slightly higherpercentages of ^C remained extractable from sediment.Land farming of the PA soil resulted in substantial reductions of net tPAH andPCP levels (Figure 15). Both the carbon and surfactant amendments inducedsimilar results. PCP reduction occurred in two of the three land farmingmicrocosms (Figure 15, 22). However, in contrast to tPAH removal, the additionof molasses slowed PCP removal.
4. Mixed Process Area Soil and Soil Holding Cell Land Farming MicrocosmStudies - The mixed soil microcosms (50% soil cell area soil and 50% processarea soil) showed no significant production of ^C-CO; from C-pentachlorophenol (Figure 16). Similar to the process area landfarmingtreatments, ^C mass balance data show negligible amounts (<1%) as C-COzwith the majority of ^C (>50%) irreversibly bound to the soil (Figure 17).
No statistically significant effect on tPAH or PCP levels was observedwith any land farming treatment (Figures 18-20, 23). Microcosms adjusted withsulfuric acid were not as effective as those adjusted with acetic acid.
VII. Discussion
A. Data quality. The variance in contaminant levels due to sampleheterogeneity and analytical procedures was shown to be less than 15% at thebeginning of the experiment. Of this variance, that portion due to analyticalprocedures is less than 5%. Most of the variance can be attributed to thedivergence of conditions in the individual respirometer flask over the 150 dayincubation period. Sample variance is clearly depicted in figures 21 -23. Thecompleteness criterion were defined to be consistent with the project dataquality objectives. In general, a completeness criterion of 90 percent datausable for specified project data uses is the completeness target for the Site. Inthis study, triplicate microcosms for each treatment resulted in a grand total of57 microcosms. Of these microcosms, only two were not useable. Therefore anoverall completeness of 96% was achieved. Classical statistical methods wereutilized for the micro-scale study phases of the Popile project to determine
14
limits on decision errors achieved in this study. Confidence level and Powervalues were at 90- 95% and the minimum detectable relative difference wasless than 10%.
Objective 1. To evaluate the efficacy of landfarming for the removal ofPAH and PCP contaminated Soil Cell and Process Area Soils.
Radiochemical tracer studies using PCP did not reveal any significantrates of mineralization to COz. However, between 40 and 60% of radiolabeledtracer was found to be inextractably bound to soil in all treatments and soils.Net PCP (contaminant levels present prior to treatment) removal wasdetermined in simulated Land Farming treatments. Significant reduction inPCP levels was achieved in all process area soil treatments, but not in soilholding cell or soil mixtures. The difference in results with radiolabel PCPtracer added and net PCP reduction indicates that the added radiolabeled-PCPwas not predictive of the behavior of the weathered PCP already present in thesoils. Similar to the PCP results, tPAH removal was found to be significant onlyfor the process area soils.
No statistically significant reduction in tPAHs or PCP concentrations wasobserved in any treatment of soil holding cell material nor mixed soils (Figures21 and 23). However, average tPAH values were found to be lower than initiallevels in certain treatments (to be discussed further in objectives 2 and 3). Incontrast to the soil cell microcosms, significant reduction oftPAH and PCP wasseen in all process area soil treatments (Figure 22). Bench-scale land farmingstudies of the PA soil are required to confirm the results of the microcosmexperiments and to determine the kinetics of PAH and PCP removal.
Objective 2. To determine the effects pH neutralization of soil cell soilusing acetic and sulfuric acids.
As indicated in objective 1, none of the applied treatments resulted in asignificant loss oftPAH or PCP from the soil cell soil microcosms. Although notstatistically significant, average final tPAH values were found to be lower thaninitial values for specific treatments: acetic acid neutralization, acetic acidneutralization with molasses, and acetic acid neutralization with witconol (figure21). Significant losses in individual low molecular weight PAHs were alsoobserved in a number of treatments (figures 10-12,15.18-20). However, thecontribution of these low molecular weight compounds to the total PAHconcentration was quite low (typically 5% or less). As a result (of the lowcontribution), no significance could be placed on the difference between theinitial and final tPAH concentration means.
15
Objective 3. To determine the effects on contaminant bioremediation ofamendments with molasses (carbon and energy source) and witconol (asurfactant).
As indicated in objectives 1 and 2, none of the applied treatmentsresulted in significant loss oftPAH or PCP in the soil cell soil microcosms.Although the acetic acid neutralization with either the molasses or witconolamendments did result in a decrease in tPAH concentration, the observedlosses were, at best, only marginally more significant than the result obtainedwith acetic acid neutralization alone (appendix A). Similarly, tPAH and PCPlosses in the process area soil microcosms were generally equal with or withoutthe molasses or witconol amendments (Figure 22). Although the results do notindicate an overall increase in contaminant removal due to the addition of theseamendments, rates of contaminant removal may have been enhanced. Anyenhancement in removal rates would have been overlooked in these analysessince only initial (day 0) and final (150 day) analyses of contaminantconcentrations were made.
Objective 4. To determine the effects on contaminant bioremediation ofmixing process area and soil cells to introduce indigenous microbes to thesystem.
During the design of these experiments the SC soil was expected to bemore heavily contaminated than the PA soil. Additionally, it was expected thatthe past treatment of the SC soil may have reduced the SC soilDs residentmicrobial community's potential to degrade PAH and PCP. Mixing PA with SCsoil was seen as a potential to inoculate the SC soil with microorganisms whichcould metabolize PAH and PCP. While the level of PCP in the SC soil wastwice that of the PA soil, the levels of PAH in the SC soil was half that in the PAsoil. The microbial biomass in the SC soil was comparable to that in the PA soil.However, soil holding cell material dilution with process area soil was found tohave no beneficial effect on tPAH or PCP removal (Figure 2 and 3).
Objective 5. To use the information generated to determine whichbiotreatment for Popile should be evaluated further at the bench engineeringscale and possible full scale operation.
According to the QAPP, during the microscale the best four systems willbe selected based on the highest ^COg generated from the P^CP spiked intothe systems. The highest relative ^COz generating system would be chosen.If none, or an insignificant amount, of CO; were generated, the choice wouldbe made based on the net reduction of contaminate PCP and PaH in thesystem. Because the systems were allow the run longer that anticipated, ordesigned, to allow for the expansion of the remediation window, the
16
mesoscale design criteria is being reconsidered, with possible QAPP revisionsunder consideration as well.
VIII. Recommendations
Based on the results of the microcosms studies and our understandingof the need to remediate the contaminated soils at the Popile site we offer thefollowing recommendation. Soil holding cell material and process area soilsshould be treated as separate problems. The results of the microcosm studiesshow land farming to be a possible remediation alternative for the process areasoil. Selected treatments which should be considered in mesoscale studiesare amendments of process area soil with organic carbon sources andsurfactants as well as with no amendments so that accurate rates ofcontaminant removal can be determined. Based on the results of this study, notreatment can be recommended for the soil holding cell material. It issuggested that alternative treatments (in addition to acetic acid neutralization)be investigated for remediation of the soil holding cell material. Bench-scaleengineering studies should be conducted to 1) verify the results of themicrocosm studies, 2) generate kinetic data on the rates of PCP and tPAHremoval and 3) evaluate engineering parameters which are difficult to simulatein microcosms (i.e., frequency of tilling).
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IX. TABLES
Table 1. Factorial experimental design.
SAMPLE TYPE
Soil Cell AreaMixture(50:50:) soil+processareaProcess Area
TREATMENTaceticacid
+
X
sulfuricadd
+
X
molasses
++
X
witconol
XX
X
aceticadd
+molasses
++
X
aceticadd+
witconolXX
X
suKuricadd
+molasses
++
X
sulfuricadd
+witconol
XX
X
+ = EPA Funded ResearchX = SERDP Funded Research
Table 2. Removal of total polycydic aromatic hydrocarbons (PAH) and p«nlachloroph«nol (PCP) from •ol microcotns (mg/kg).
Microcsom Amendmentinitialno additivesmdassaa (.03%)wttconol(3%)tiffuric acid ax^usted (1M)sutfuric ack) adjusted * motessassulfuric add adjusted * wttcondacaUc acid adjusted (1M)•catfc acid adjusted + molassesacafc add adjusted * wDcond
Total PAH145912041104*378144312961314177399311035
280412386118016527811780
1848x22708361170
Land
% PAH loss
241
103202046043
Fanning MfcSolCI
BaPaa27752825355318153815
SVCOSW
PCP10018
2021158293615275*1691311110572149219511181341133349*508174*21
WPCPtou
000000000
ProceuAr—ToM PAH % PAH teas BaPaq PCP %PCPIoaa
no additivesrndaBMM (.03%)wMcond(3%)
2093*268133*15238*86160*80
4294
92
50*80 100
34*13 360 100
MhadScaTotal PAH »PAHIoa« BaP«Q PCP %PCPIoaa
initialnoaddttvesmdauaa (.03%)sulfuric add adjusted <• molassessulfunc add ad|usled * wtcondacoUc add adjusted * mo—s—.acaUc add adfusted + witeond
1776*2361707*10664349*45681737*13762054*12896931355538*317
4020
6170
36319935421412
78*32169*141
881*1121371*362354*187132*88111*109
000000
Benio<a)pyreneeculvateiK (BaPeq)«r«b««^onthelarice<»)tv»««Kyfac»CT»(TEn»rtu««d«»ts<db»L^% PAH and % PCP toaa Is daHnad aa: Initial coocentraBon minus mterocoam amendrmnt LUlcanliaUun dMded by MBal cancannaBon amaa 100values represent the an annar (n«3) ± a standard deviationNDhdlcate*noldon*
18
Table 3. A summary of total PAH and PCP losses.
NAMWSAASAAMSAAWAAAAAAMAAAW
Process AreaPAH PCP
NAMW
MixedPAH PCP
NAMSAAMSAAWAAAMAAAW
Soil CellPAH PCP
---------
XX XXXX XXX XX
----
XXXX
- (<50% loss), XX (>50% loss)
Table 4. Total average % loss per soil area per microcosm treatment.
Land Farming___PAH PCP
Soil Cell AreaProcess AreaMixed Soil
199223
0800
Values reflect the average of all microcosm amendments (n=9)
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X. APPENDIX
Appendix A. Results of an LSD-ANOVA for the comparison of total PAH concentrationsacross treatments, initial versus final concentrations.
Land Farming________Treatment_____________Soil Cell Process Area Mixed
no additives 0.716 0.000 0.959molasses (.03%) 0.985 0.000 +witoonol (3%) 0.865 0.000sulfuric acid adj. (1 N) 0.634sutfuric acid adj. + molasses + 0.976sulfuric acid adj. + witeonol 0.726 +acetic acid adj. (1 N) 0.43acetic acid adj. + molasses + 0.422acetic acid adj. + witeonol 0.468 0.360
(+) indicates a treatment mean greater than the initial meanp values < .10 indicate significance at an alpha of 90%
Appendix B. Results of an LSD-ANOVA for the comparison of total POP concentrationsacross treatments, initial versus final concentrations.
________Land Farming________Treatment Soil Cell Process Area Mixed
no additives +molasses (.03%) +witeonol (3%) +sulfuric acid adj. (1N) +sulfuric acid adj. + molasses +sutfuric add adj. + wftconol +acetic acid adj. (1N) +acetic add adj. + molasses +acetic add adj. + witeonol +
0.000 +0.003 +0.000
(+) indicates a treatment mean greater than the initial meanp values < .10 indicate significance at an alpha of 90%
21
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XI. FIGURES
Figure 1. Obtaining core samples.
_j_|__-^^ Core extrusion
Extrusion of Process area soil Soil core geological logSoil core geological log
Figure 2. Sample preparation.
Breaking up cores Sieving soil from cores
Sieved soil Homogenized soil stored a 5 °C
Figure 3. Comparison of results of contaminant analyses.
2500
2000 -
1500
1000
500 -
0
Ace Flu Phen Ant Fluor Pyr BaA Chr Total PCP
Figure 4. Construction of soil holding cell and initial chemical and physical characterization.
Total Soil Volume yd3
Moisture Content (%)
Pentachlorophenol mg/kg
Total PAH's mg/kg
BaP Equivalency mg/kg
pH units
MEAN±SD
Approx. 66,000
84.9 ±0.72
55.6±8.1
2093.3 ± 267.6
75.8±11.1
7.07
MEAN ± SD
Approx. 66,000
87.5 ±1.3
100.2 ±8.0
1458.7 ±204.3
267.1 ±41.7
9.57
Viable Microbial Biomass Estimates1e+8
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1e+7
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15 -
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s^^
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Figure 6. ^C-Acetate mineralization study.
Time(days)
Figure 7. Soil Cell soil pH neutralization experiment.
10
IN Sulfuric Acid Additions
0.5 1.5
mL of Acid
14,Figure 8. C-PentachlorophenoI mineralization in soil cell land farming microcosms.
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Day
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Molasses
Witconol
Sulfuric AcidAdjusted
Sulfuric AcidAdjusted,Molasses
Sulfuric AcidAdjusted,WitconolAcetic AcidAdjustedAcetic AcidAdjusted,MolassesAcetic AcidAdjusted,Witconol
Soil Cell Land Farming Microcosms
Soil Cell Land Farming Microcosms
Soil Cell Land Farming Microcosms
Figure 13. ^C-Pentachlorophenol mineralization for Process Area soil land farming microcosms.
3% Witconol
0.03% Molasses
No Additives
Days2% Impurity of^C-PCP
Figure 14. Mass balance radiolabeled PCP Process Area land farming microcosms.
140
•Combustible Sediment
nExtractable Organic
DKOH post-acidification
•Extractable Aqueous
•Carbon Dioxide
115
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Soil Mixture Land Farming Microcosms
^ <%^ 0s' </ ^^~
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^ <?°
Figure 21. Statistical comparison of soil cell treatment means.
Soil Cell Area
?
6000
5000
4000
3000x
°: 2000
1- 1000
0
-1000
°B -oINIT M SAA SAAW AAAM
NA W SAAM AAA AAAW
1200
1000
800
3 600
0.
^
400
200
0
-200
-400
INIT M SAA SAAW AAAMNA W SAAM AAA AAAW
Figure 22. Statistical comparison of process area soil treatment means.
Process Area
^buu
2200
^ 18000)
? 1400
$S 1000
>° 600
200
-200
70
cr\bU
50
40"5i
g 30
^ 20
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Figure 23. Statistical comparison of mixed process area and soil cell treatment means.
Mixed Soil
11000
9000
-5, 7000
5000
^ 3000
1000
-1000
2200
1800
1400
1000
600
200
-200
-600
J8INIT M SAA SAAW AAAM
NA W SAAM AM AAAW
INIT M SAA SAAW AAAMNA W SAAM AAA AAAW
Comment Resolution for the Microscale Phase of the Treatabilitv Study
The resolution to the microcosm study comments are resolved as follows:
EPA (Dallas} Comments
Comment:
Describe the results in terms of the stated objectives. For example: Objective 2. To determinethe effects... acid. The results demonstrated that the effect ofpH neutralization .... I want to ensurewe clearly show that the objectives were or were not met.
Resolution:
The Waterways Experiment Station agreed to review and clarify the language so that theobjectives' resolution are clearly stated in the document, by adding a bullet summary of theobj ectives and resolution of the obj ectives .For each section of the report in which the obj ectives ofthe study are defined, an "objective statement" is accompanied by bullets to summarize theapplicability of that section to the overall experiment objective. This has been incorporated into thefinal report.
2. EPA (Add) Comments.
Comment:
The Ada laboratory agrees with the conclusions.
Resolution:
Concur.
3. ADPCE Comments
Comment:
a. The WES Study, Ada treatability study and the START treatability studied all indicate areduction in PAHs and PCP in the Soil cell material, even though WES in the VII Discussion sectionindicates that no statistically significant reduction in total PAHs and PCP was observed in anytreatment of soil holding cell material nor mixed soils. Therefore ADPC&E requests additionaldetail data as follows:
i. An illustration, in table form, of the confidence level of each microcosm test of the SoilCell soil the Process Area soil and the mixed soil including the total PAR and PCP.
ii. Data in table form for each compound of the PAHs showing initial and treatedconcentration. Include standard deviation with each compound.
Resolution:
3 .a.i. and 3 .a.ii.- The confidence level associated with each treatment microcosm is incorporatedinto the graphical presentation of the data, although it may be difficult to see. The raw data use togenerate the graphical presentation in the report has been made available and incorporated asappendices A through D in the final report. The data associated with the initial and final experimentconcentration is presented in a similar fashion. Again, the raw data will be will be made availableand incorporated as appendices in the final report.
Comment:
b. ADPC&E recognizes that homogenization of samples is a difficult chore and that WES madespecial effort to insure as much homogeneity as possible. It still remains that a 12% variation insamples could appreciably affect final results and mask the significance of final results.
Resolution:
A discussion of the data quality as it relates to the homogenization of the soil is found in SectionVII. Discussion, of the final report as follows: Data quality. The variance in contaminant levelsdue to sample heterogeneity and analytical procedures was shown to be less than 15% at thebeginning of the experiment. Of this variance, that portion due to analytical procedures is less than5%. Most of the variance can be attributed to the divergence of conditions in the individualrespirometer flask over the 150 day incubation period. Sample variance is clearly depicted in figures21-23. The completeness criterion were defined to be consistent with the project data qualityobjectives. In general, a completeness criterion of 90 percent data usable for specified project datauses is the completeness target for the Site. In this study, triplicate microcosms for each treatmentresulted in grand total of 57 microcosms. Of these microcosms only two were not usable. Thereforean overall completeness of 96% was achieved. Classical statistical methods were utilized for themicro-scale study phases of the Popile project to determine limits on decision errors achieved in thisstudy. Confidence level and Power values were at 90- 95% and the minimum detectable relativedifference was less than 10%.
Comment:
c. The WES studies do not identify whether conditions in the Soil Cell are Aerobic orAnaerobic. Anaerobic conditions would result in much slower breakdown rates caused by differentbacteria. This may show itself by indicating no breakdown of PAHs within 150 days.
Resolution:
3 .c. While the point of this comment is not clear, the following rationale may help to clarify thequestion/statement. The main objective of the study was to conduct an aerobic study to determinefeasibilty of remediating soil by landfarm technology as it may be applied to the original technicalcontracting documents in the framework of a technically achievable specification and contract.Conditions within the soil cell, prior to invasive sampling are not known (may/may not be anaerobicdepending on many factors, primarily oxygen availability). The original specification and the RODassumes that the soil could be treated in an aerobic environment without any consideration of soilcell v. process area soils. The microbial consortia, at the point of soil removal, would be a functionof those conditions, however the consortia would change very rapidly once exposed to ambientoxygenated conditions, as oxygen is highly toxic to anaerobes. An acclimation process would beginimmediately as the new viable consortia began establishing in the aerobic environment. Somestudies show that within 30 days microbial colonies usually have repopulated, and began to stabilize,putting the study consortia on an even playing field, when comparing bioaugmentation andindigenous microbes. In conclusion, the point is that anaerobic bioremediation is not aconsideration (based on the original design considerations), but variability between the twoconsortia may be. The results of the soil mixing (soil cell and process area soil) tend to indicate thatthis is not the case, and a "toxic" effect may be the reason for the inhibition, but this is notconclusive.
US Army Corps ofEnginers. Waterways Experiment Station
Comment:
Minor adjustments and "clean-up" type changes are as follows:
Resolution:
1) in the Table of Contents, correct the page numbers
2) correct page numbers in the document
3) add "Sample" before Coring in the Methods section.In the Summary section:
4) correct subscript for C02
5) reverse 92-94% to 94-92% to reflect data in tableIn the Objectives section:
6) delete the reference to mixing SC with PA soil as a treatment to better match table 1.
7) change the surfactant addition to the 4th treament instead of the 5thIn the Methods section:
8) delete the sub heading "Sampling" and place Sample in front of the Coring sub-heading.
9) change the references to figures 2 and 3 to 1 and 2.In the results section:
10) change the reference of figure 2 to 1 and of figure 1 to 4.
11) chnage the soil moisture numbers for SC and PA soils to 87 to 85% to reflect what is in figure4(1).
12) change the reference for figure 6A to 5A
13) change the reference for figures 5A and 5B to 5B only
14) Add a sub heading "Biotreatments" before the pH neutralization heading
15) change the sulfuric acid volume from 0.075 ml to 0.75 ml
16) change the text describing mass balance results from solvent extactable to "extractable organic"to correspond to figure legendsIn the discussion section:
17) change significant reduction oftPAH and PCP was seen to "reductions in tPAH and PCP were"
18) Under the objective 4 listing, change the reference for Figure 2 and 3 to tables 2 and 3.
19) Add the sub-heading Recommendations after the objective 5 listing.
20) add a reference to table 4 in the sentence "based on the results of this study, no treatment canbe recommended for the soil holing cell material.In the Figure legends:
21) change figure 1 to 4, 2 to 1, 3 to 2 and 4 to 3 to better fit the text (order of description)In the tables:
22) delete table 4 and change table 5 to 4.In the appendices:
23) correct the appendices to reflect the table of contents descriptions.